Numerous processes and devices rely on monolithic structures acting as supports for a catalyst layer. Several methods are used to create the monolithic structures, the two main routes being ceramic extrusion and spiral wound foils. Monoliths can be created by extruding a ceramic to form a ceramic monolith having channels passing through the body of the monolith structure. Monoliths can also be created from metal foils, particularly corrugated metal foils, which are spiral-wound to form a support, and a catalyst or adsorbent then coated down onto the support. This method is often hampered by clogging or poor coating results when the structures or channels on a support become too small. In other words, monolith microstructures can reach a size below which applying the coating becomes impractical.
Moreover, the effectiveness of many processes is proportionate to the amount of available surface area, particularly in catalysis or adsorption. Decreasing the size of channels in a monolith leads to more surface area for reactivity, but there are limits to how small the channels can become before coating becomes impractical. Moreover, processes that require a significant amount of surface area of catalyst/adsorbent are typically hindered by large pressure drops in the reactor. For example, rapid cycle swing adsorption processes with extremely short cycle times typically require structured adsorbent beds (rather than randomly packed beds) to reduce the pressure drop in the bed. Laminar flow in these systems can be ideal if the adsorbent can be aligned in a straight channel fashion. Coating straight channel structures (e.g. monoliths) with adsorbent is one option, but remains challenging due to the small size of the channels.